Christopher Kyba 🇨🇦🇪🇺Mar 2

15 years ago, I co-authored my first paper in the field of #LightPollution studies: https://doi.org/10.1371/journal.pone.0017307

Up to that point, work on artificial brightening of the sky had been done almost entirely by astronomers, who (for obvious reasons) weren't really interested in cloudy nights. But because I was involved closely with ecologists from the Leibniz Institute of Freshwater Ecology and Inland Fisheries @LeibnizIGB, we realized that it's also important to measure the extent to which overcast and clear nights differ.

Through a bunch of twists and turns I now work on #RemoteSensing using nighttime light, but that was the paper that launched me into this direction.

Show threadChristopher Kyba 🇨🇦🇪🇺Mar 2

Most people in brightly lit countries probably take for granted that clouds are bright at night, but this is completely unnatural. You can see it better in this pair of photos we published in a later paper (titled "Red is the new black"): https://doi.org/10.1111/j.1365-2966.2012.21559.x

This probably matters a great deal for nocturnal animals, because it's a reversal of an environmental condition that existed during the hundreds of millions of years that life evolved.

Show threadJames Endres HowellMar 2

@skyglowberlin I teach large university science courses. Hundreds of fairly privileged students in the room. It has been my habit to ask them to raise their hands if they have ever seen the Milky Way.

The results have always been disappointing. Over the past 20 years it has gotten worse and worse. Recently many students don't even know what I mean by the question, and I have to explain what a dark sky looks like.

"Raise your hand if you have ever been awed by a clear dark sky full of countless, countless stars." Always less than 5%.

Show threadChristopher Kyba 🇨🇦🇪🇺Mar 2
@jameshowell Yeah, it's rough to hear things like that. I remember hearing from some people from (I think) the US NPS that they created a scene with virtual reality goggles to show people what a natural sky looks like when you are dark adapted, and a lot of the people who experienced it didn't believe that it could be real 😥
Show threadJames Endres HowellMar 2

@skyglowberlin When I teach about retinal physiology, it breaks my heart. Often there isn't a single student who has ever experienced vision after true dark adaptation.

It turns out that—it takes time, but it's real—you can see by starlight. And the faintest stars you see? That's a single rod cell detecting A SINGLE PHOTON. Your retina is that sensitive.

Before 1879 this was an absolutely universal human experience. Now it's exotic, unimaginable.

Show threadChristopher Kyba 🇨🇦🇪🇺Mar 3

@jameshowell Yup. If I won the lottery, one of the studies I would love to fund would be to see whether adults who grew up in rural settings have superior night vision to those who grew up in the city.

If you never train your visual system to see with rods only, does it still develop normally?

Show threadglasspshrMar 4

@skyglowberlin @jameshowell I’ve been an amateur astronomer since I was 11 and had a home darkroom for photography soon after. I’ve let people know what can be done and seen in low light.

One time, winter hiking in New Hampshire, my flashlight batteries died and I hiked another 2 miles under just the illumination of a clear night sky. Mars was the brightest thing out.

Show threadChristopher Kyba 🇨🇦🇪🇺

@glasspusher @jameshowell There's a path through the woods in Brandenburg that I've walked several kilometers along on starlit nights without a moon. I couldn't actually see the ground because of the foliage, but I could follow the path because of the lighter areas between the trees.

This isn't a great idea, though - if someone had dug a big hole in the ground I would likely have fallen in. But it shows what's possible when you know the area and the pathway is flat.

Mar 4 at 3:12pmWeb
Show threadglasspshrMar 4

@skyglowberlin @jameshowell

Yes, when I did the above hike, I could see the trail in front of me- footsteps in the snow.

Back when I lived in Oakland, one night I walked my regular jogging trail through a park( very narrow). I was under tree cover which made it darker, as I was looking for luminescent mushrooms. I found I could keep on the path by feeling, as I walked, that the ground was harder on the trail than the edges.

Pushed the limits of what I could see in low light, and noticed that my other senses were filling in the experience more.

Show threadChristopher Kyba 🇨🇦🇪🇺Mar 4
@glasspusher @jameshowell Yes, walking slowly and feeling the ground your feet is very important in such a situation.